Grit Has a Negligible Effect on Success Compared to Intelligence

> The Short Grit Scale (Duckworth & Quinn, 2009) was used as a measure of grit and was administered to most of the NLSY participants in 2013 (6,476 of the original sample of 8,984 in 1997). It consists of 8 items in total, 4 items for each grit facet—perseverance and consistency of interest. Sample items are “I am diligent” (perseverance) and “new ideas and projects sometimes distract me from previous ones” (consistency of interest). Answers are given on a scale from 1 (very much like me) to 5 (not like me at all).

This is like measuring intelligence by asking people whether they identify with statements like "I am a fast learner." Most people aren't very self-aware. I often find that people that work less hard (in general across a wide range of things) often self-identify as having more grit because people work hardest when they work on something they are motivated to do, but being able to work superficially in the absence of motivation for long periods of time makes people feel they have more grit.

My suspicion is that grit (in the sense that matters, not whatever the grit researchers have been pushing) is mostly indistinguishable from intelligence as it's typically measured. I'd be shocked if most intelligence tests don't already do a better job of determining grit (in terms of the level of perseverance you could expect from someone) than asking someone if they are diligent.

1. Those R squared numbers in table 2 are quite low. The statistical analysis itself is painfully basic. I'm a statistician, and I've a bookshelf full of excellent books written by statisticians who publish in psychology, so they should have been able to find someone to beef up the analysis a bit. That said, psych publications is also notorious for bad data analysis. I'm an outsider to this field, but this feels like an omission.

2. The paper doesn't use any causal inference techniques despite making a clear causal claim in the title. They use simple linear regression, which is not a causal model unless causal assumptions are made explicit. In my book this is a grave sin, one avoids making causal assumptions that might be hard to defend, fits a model with linear correlation, then makes causal conclusions. To understand what I mean by causal model, read this (these techniques are well-known and if the authors' defense is that they don't know them, it reflects badly on them): https://en.wikipedia.org/wiki/Rubin_causal_model

3. It is worth thinking about what the intelligence assessment, the AFQT test, actually quantifies. One critique of AFQT is that it is more of a measure of literacy than intelligence. Read more here: https://en.wikipedia.org/wiki/Armed_Services_Vocational_Apti.... Maybe the title should be "Having parents that make sure you can read by age five has a greater effect on success than grit."

4. The AFQT and other intelligence tests have a pesky problem of having averages that change in time. This suggests that much of what they measure is not innate, but learned.

5. Social psychology is plagued by a reproducibility crisis. I'm sorry to say, their papers, no matter how provocative the findings, have to be viewed with great skepticism. https://www.psychologytoday.com/us/basics/replication-crisis

6. The paper says social economic background has a significant effect, but about the same effect on pay as intelligence. That seems to conflict with a pile of research that says that social economic background is the strongest predictor of success. To say that IQ is just as important as your parents' wealth is pretty eyebrow-raising.

Very challenging to evaluate without paying $40 to read the paper. They mention a difference in how they group the subjects (by intelligence). My gut take (often wrong!) is that they're grouping the subjects in some way that pushes part of my understanding of grit into intelligence.

"Intelligence" was measured by an individual's performance on the "Armed Forces Qualifying Test" (AFQT).

"Grit" is self-reported on the "Short Grit Scale" which asks participants to rate themselves from 1 to 5 on statements like "I am diligent."

"Success" was measured by level of education attained and hourly wage rate in 2015.

Control variables include: Gender, household income as a child and level of education by parents. Study participants were born in the early 1980's.

Top-level findings:

> Although in our representative sample of the American population grit does explain educational and job-market success over and beyond other predictor variables such as socioeconomic status, intelligence, and the Big Five personality characteristics, its absolute effects are rather minimal. In particular, its effects are negligible in comparison to the effect of intelligence. Finally, the effects of grit were also considerably weaker than the effects of conscientiousness.

This isn’t particularly shocking. There aren’t a lot of high paying jobs for dumb people and nepotism doesn’t scale enough to make up for that.

>The measure of intelligence was taken from the 1999 wave, the measure of grit was taken from the 2013 wave, and the measures of suc- cess from the 2015 wave. Thus, intelligence was measured when the participants were aged 15–19, grit was measured when the participants were aged 29–34, and success was mea- sured when they were aged 31–36.

Jesus.

https://www.gwern.net/docs/iq/2020-zissman.pdf

Eating soup with a fork is still a success with enough intelligence.

Pfffft. Spoon-fed geniuses raised with only forks was a cruel joke.

Let me guess... For an encore, they'll do a study that says AI is more successful.

A suckers iterated ever minute on the Internet with a path/information like that.